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Provides protection and sometimes support


single-layered epidermis, sometimes with cuticle


cuticle, epidermis, connective tissue (dermis), layer of iridocytes, and more connective tissue


epidermis (hypodermis) that secretes a complex cuticle, inner procuticle (protein and chitin) and outer epicuticle (protein and lipid for waterproofing)


flexible or calcified or sclerotized: often serving as an exoskeleton


Must be shed to allow growth


have epidermis (stratified epithelium of ectodermal origin) and dermis (connective tissue of mesodermal origin)


Epidermis keratinized in terrestrial forms (scales, feathers, hair)

Dermis bone

armor —> flexible scales) (antlers


structural (physical structure affects light) or pigment based (chromatophores)

crystals of g or p

Melanins, carotenoids in xanthophores), iridophores

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